on my 96 deville my left tail light will not work. The bulbs are good and when i hit the brake the lights come on but if im not holding the brake they will not stay on. Does anyone know what this could be?

You could test for 12v on socket terminals, with bulbs removed, with voltmeter or test light. also check ground terminal which contacts side of bulb. Sometimes socket contacts will collapse which can cause lighting concerns also. Test with park lights and hazards on so all wires are powered up.

????? I think you need to find someone locally to help you, post what you find, and the "forum" can still try to guide you. If you have no fundamental knowledge, getting an basic automotive text book (VoTech) maybe helpful.

on my 96 deville my left tail light will not work. The bulbs are good and when i hit the brake the lights come on but if im not holding the brake they will not stay on. Does anyone know what this could be?

i think all you need is a new bulb.... in that bulb there is two lights. the tail light is bad, and the brake is good..... change the bulb, if you can or ask for some help. its pretty simple. your owners manual might assist you with this
rickyd

On my 97 deville the left tail and left marker are not working. If I put on the right turn signal and short the left tail and right turn wires together at the trailer connector then I get a blinking left tail and marker. In the middle of the hidden inboard BIG fuse panel there is a 50amp fuse which will turn off the right marker and tail light. I haven't been able to find a blown fuse anywhere. I also haven't found a schematic for the light switch either. I've pulled all the relays and haven't found one that controls the right tail and marker either.